The invention relates to a package, for example, for surgical instruments and products, formed from a strip of plastics and a strip of paper or the like.
It is well known, for example, for surgical instruments, syringes, catheters and similar to be sterile-packed, in order to ensure that at the moment of use of the packed goods sterilisation does not have to be carried out. Moreover, this ensures that the packed goods are destined for single use only (disposed of after use), since it is on this premise alone that an optimum in terms of sterility can be achieved by this method.
After packing the goods, which as a rule is effected without the use of vacuum, the finished packages are subjected to a sterilisation process. The application of heat corresponding to the temperature of steam, i.e. the use of heat for sterilisation is not particularly favoured, because the necessary heat can have a disadvantageous affect upon both the component elements of the package as well as upon the packed items. For example, the strip plastic adopted or the plastic components of the packed goods soften at the sterilisation temperature. For many medicines, syringes or corresponding products the use of elevated temperatures is out of the question.
Sterilisation is effected, therefore, by gassing with a germicidal gas. For this purpose, the packages are placed in an enclosed container and the air within the packages is replaced to an adequate degree by the germicidal gas introduced into the container by alternate application of a partial vacuum and superatmospheric pressure.
The process of gas exchange is achieved by the fact that the strip paper of the package is such as to allow the gas to permeate through, whilst possible germs are retained by the strip paper.
The residual quantities of gas provide adequate protection against renewed bacterial contamination until the packages are used or consumed, assuming the package is adequately sealed.
It now presents no problem to join the strip of paper and the plastic foil sheeting together, preferably by sealing in a manner in order to ensure an adequate level free from leakage. The edge to which the two strips of foil sheet are joined together for each package, has to have a suitable width for this, whereby, as a rule, approx. 5 millimeters is considered sufficient. By a suitable sealing operation which is usually made on the application of heat and whereby a sealing tool presses the edge on one side against a support, which is arranged on the other side, a tight seal can be easily accomplished.
When a package of this type is to be opened, it should be possible to do so without the use of additional tools, and it is required to be able to peel off the strip of plastic foil and the strip of paper from each other, for which, if need be, a tab or another projection is used for the opening operation.
The condition of this so-called ability to peel presupposes that the bond between the two component part of the package is not too firm. If the seal or similar is bonded too tightly, the strip of paper will not peel off, adversely affecting the opening operation.
In addition, in peeling the two sheet materials apart, there is the problem that fibres and lumps of fibre will be torn out of the strip paper in the event of the bond being too strong, possibly causing the fibres to fall on the packed goods, i.e. the surgical instruments, which following operations, can lead, for example, to inflammation and other undesirable consequences for the patient. Therefore, the bond between the strip paper and the strip of foil sheeting is to be made such that, on the one hand, the peelability is retained, and, on the other hand, no loose fibres occur during peeling.
However, in so doing, attention must be paid to the fact that the strip paper is made in such a manner that it is basically gas-permeable, which virtually excludes the use of agents which are suitable for increasing the cohesion of the fibre-bond of strip paper. Such agents, like glue or similar, which are otherwise used to increase the strength of the fibre bond of the material would have a disadvantageous affect upon the penetration of gas.
A reduction of the bonding effect of the sealing between the two strips now has the result that during the above described gas exchange, in which the package is subjected to repeated suction, on which the package inflates, the seal is adversely affected, i.e. that the package will become unsealed. Such unsealed packages can be difficult to detect externally.
When mention is made in the preceding and following text regarding the seal in context with the bond of the strip paper with the plastic foil sheeting, this is not taken as a limiting concept. As a rule, sealing is indeed used, but it is also possible to replace the sealing by an adhesive operation. Even bonding agents, which are considered superior to "welding", can be adopted.
This means with which the effect of a sealed seam is intensified or lessened is known per se. A proposal was made for a package of a similar type in the specification of West German patent application No. DE-AS 26 08 777, but was for resolving another object being that the welding base bearer which operates in conjunction with the sealing tool is designed such that it features a plurality of pyramid-shaped raised projections, thus producing a seal for which the individual elements of the seal consist of a plurality of spots.
Furthermore, it is also intimated in the above mentioned document the use of a welding base which has a plurality of pyramid-shaped depressions, so that the sealing elements between the two strips receive a net-like form. The adoption of the described welding base is made in the mentioned document for the purpose of avoiding adhesion of the package to the welding base. However, it has been found that in using the mentioned means, when the elongations of the individual sealing points or lines remain sufficiently small, the bonding effect of the seal is limited, such that a good "peelability" is achieved.
It is further known to seal the edge of the packages in question so that several seams are arranged on the edge, whereby the sealing seams then surround the formed receptive cavity as the case may be. The use of a plurality of such linear sealing seams running parallel to the edge increases "sealability" and improves the bond as well between the two strips. On peeling one of the strips from the other, however, it unavoidably results in a tearing out of the fibres of the strip paper, with all the disadvantageous consequences.